var username = "root",password = "123456";
console.log(username === "root" && password === "123456")
var age  = 65;
console.log(age >= 60 || age <=12);
var user = 1143;
console.log(user == 123 || user == 456 || user == 789);
var a =5;
a > 10 && console.log(num);
a > 2 || console.log(num)
var age = 51;
age < 18 || console.log("成年");
age > 18 && console.log("成年")